Children given a hormone growth factor alongside chemotherapy for the aggressive cancer neuroblastoma are less likely to suffer a potentially deadly side-effect, according to a major international study published today (Tuesday) in the Journal of Clinical Oncology.

The hormone, called granulocyte colony-stimulating factor (GCSF), was already known to boost production of white blood cells. But this Cancer Research UK-funded study is the first large randomised trial to show it can reduce the complications associated with low white blood cell count in children treated for advanced forms of neuroblastoma.

Around 100 children are diagnosed with neuroblastoma** every year in the UK, usually under the age of five. Overall six out of ten children are successfully treated, but for children with advanced forms of the cancer it is very difficult to treat successfully.

Children diagnosed with advanced forms of neuroblastoma are given particularly intense treatment that combines surgery, radiotherapy and chemotherapy.

But this treatment often carries the side-effect of 'neutropenia' - a low white blood cell count. As white blood cells are key components of the immune system, patients who develop neutropenia during treatment are more susceptible to other diseases and complications.

Professor Andy Pearson, lead author of the paper and Cancer Research UK's professor of paediatric oncology at The Institute of Cancer Research (ICR) and The Royal Marsden NHS Foundation Trust in Sutton, said: "Patients given GCSF immediately after chemotherapy treatment had fewer problems associated with neutropenia, such as fever, infections, days spent in hospital or on antibiotics and gastrointestinal issues.

"Our team previously identified the high dose chemotherapy regimen that is already saving the lives of many children with high risk neurobastoma, and in this study we report finding a new therapy to reduce side-effects for these patients.

"On the strength of these new trial results, all children receiving intense chemotherapy to treat high-risk neuroblastoma will now be given GCSF."

The work builds on promising results from an earlier study, also funded by Cancer Research UK and led by Professor Pearson at the ICR, which found that giving doses of five chemotherapy drugs - cisplatin, vincristine, carboplatin, etoposide, and cyclophosphamide - more frequently offered the best hope of a cure.

This therapy is now being taken forward as the treatment for children in Europe through the International Society of Paediatric Oncology, Europe Neuroblastoma Group (SIOPEN)***.

Kate Law, Cancer Research UK's director of clinical research, said: "The results of this promising trial mean that children across Europe diagnosed with neuroblastoma will receive a more effective treatment for this disease.

"Cancer Research UK is the largest single funder of children's cancer research in the country and is at the heart of an international research effort leading to rapid improvements in children surviving cancer with the fewest possible side effects.